If an opponent’s claws vastly outsized its own, the smaller arachnid would make itself scarce after a brief skirmish. But an evenly matched set of claws usually meant a clash could run five to 10 minutes—until one conceded defeat and fled, or until one got eaten.

Curiously, some smaller individuals had claws bigger than their bodies, which possibly confused their opponents.

“If you want to advertise how big and bad you are, it pays to lie—to make it look like you’re bigger than you really are,” says Chapin. But “lying is risky, because you might get cannibalized.”

Michael Seiter, a tailless whip scorpion expert at Austria's University of Vienna, say the study is the first to statistically describe the arachnids' conflicts—an improvement upon random observations in the field.

The findings are “pretty cool and an excellent first step in understanding their behavior in natural environments where the specimens interact all the time.”

Love-Hate Relationship

Study leader Chapin was also surprised that tailless whip scorpions were aggressive regardless of the sex or age of their opponent—ie. males matched with females and older animals matched with juveniles displayed the same violence. (Also see "Male Spiders Risk Death By Courting the Wrong Females.")

He’s not sure how males and females get past their fighting to, er, more delicate interactions, but has a theory that the females might be testing the males by fighting with them.

“It could be that all interactions start off with this aggressive way," he says, "and maybe an hour later it changes into courtship."